Expandable tube, and heat exchanger

ABSTRACT

An expandable tube comprising a bendable body that includes a plurality of adjacent longitudinal passages each having adjacent longitudinal sections positioned inwardly of the tube interior, each section preferably having adjacent edges positioned inwardly with respect to the tube and hinge means at adjacent edges for expansion of the tube body at the hinge means under internal pressure without substantial lateral distortion of the individual sections between the hinge means. A heat exchanger comprising a heat conducting fin having an opening therein of noncircular configuration and a tube of similar noncircular cross section expanded to fit snugly into the opening in which the tube has the structure set out above.

United States Patent {72] lnventors [.22] Filed Apr. 8, 1969 [45] Patented Sept. 7, 1971 [73] Assignee Modine Manufacturing Company [54] EXPANDABLE TUBE, AND HEAT EXCHANGER FOREIGN PATENTS 539,529 9/1941 Great Britain Primary Examiner-Frederick L. Matteson Assistant Examiner-Theophil W. Streule Attorney-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: An expandable tube comprising a bendable body that includes a plurality of adjacent longitudinal passages each having adjacent longitudinal sections positioned inwardly of the tube interior, each section preferably having adjacent edges positioned inwardly with respect to the tube and hinge means at adjacent edges for expansion of the tube body at the hinge means under internal pressure without substantial lateral distortion of the individual sections between the hinge means. A heat exchanger comprising a heat conducting fin having an opening therein of noncircular configuration and a tube of similar noncircular cross section expanded to fit snugly into the opening in which the tube has the structure set out above.

PATENTED SEP 71ml sum 1 2 g mm 'NVENTQRs JACK C.DUDLE BY#%MM9 U ATTORNEYS,

PAIENIEnsEP nan 3,603,884

SHEET 2 OF 2 This invention relates to a compact expandable tube comprising a bendable tube body having a plurality of adjacent passages, each of which has adjacent longitudinal wall sections with the result that the bend of the tube body on expansion takes place at the wall sections.

The invention also relates to a heat exchanger comprising a fin having a noncircular opening and a tube of this type expanded to fit snugly in the opening.

The invention will be described as related to the embodiment shown in the accompanying drawing, of which:

FIG. 1 is a transverse section through a contracted or collapsed heat exchanger tube embodying the invention with the adjacent portion of the fin shown in partial elevation.

FIG. 2 is a view similar to FIG. 1 but with the tube expanded to fit snugly within its opening in the fin.

FIG. 3 is a transverse section through a second tube embodiment.

FIG. 4 is similar to FIG. 3 and illustrates a further tube embodiment.

In the embodiment of FIG. 1 the expandable tube before expansion thereof is located in an opening 11 in a heat exchanger metal fin 12 of customary construction which is usually of aluminum, copper or the like. The opening 11 in the illustrated embodiment is generally oval with flat substantially parallel sides 13 and rounded ends 14. As shown in FIG. 1 the tube 10 is positioned in the opening 13 in compact or collapsed condition for later expansion snugly into the opening as shown in FIG. 2.

The compact expandable tube comprising a bendable tube body such as one made of metal and particularly one of aluminum or copper with this body comprising adjacent longitudinal tube sections I5, l6, l7, l8 and 19 on one side of the tube and similar sections on the opposite side. The longitudinal sections which extends lengthwise of the tube have adjacent corner edges 20, 21, and 22 with certain of these edges as illustrated at 21 positioned inwardly with respect to the collapsed tube. These edges 20, 21 and 22 are provided with hinge means for expansion of the tube body at the hinge means under internal pressure without substantial lateral distortion of the individual sections 14-19 between the hinge means. Thus the collapsed tube 10 can be expanded from the position shown in FIG. I to the position shown in FIG. 2 without substantial lateral distortion of the individual sections themselves. In the illustrated embodiment each hinge means comprises a thin section of the tube body that in the illustrated embodiment is provided by longitudinal grooves 23 on the interior of the tube.

Also in the FIG. I embodiment the tube'is provided with a transverse web 24 between the sides of the tubes that are adjacent to the parallel sides 13 in order to prevent expansion of the tube at tho web.

Normally when a hollow expandable tube is expanded by internal pressure such as air pressure the tube tends to assume a circular shape under the forces of expansion. In this embodiment where bending of the tube is concentrated at the hinge means the tube will expand to fit the series of openings 11 in successive fins (of which only one is shown) without losing the flat configuration of the opposite sides of the expanded tube. Because the sections themselves do not bend between the hinges it is very simple with this invention to get fiat parallel opposite surfaces in the expanded tube as shown in FIG. 2. Although it is true that the fins l2 themselves would serve to restrict outward expansion of the side walls of the tube this invention also prevents outward expansion beyond the flat of the sides in the area between adjacent fins.

The embodiment shown in FIG. 3 which for simplicity shows only the tube after expanding and in the absence of the fin is similar to the embodiment of FIGS. 1 and 2 in that it also contains parallel fluid passages 25 and 16 separated by a web 27 similar to the web 24. However, in this embodiment the grooves 23 that provide the thin hinge sections are omitted and the outwardly movable tube sections 28 blend smoothly and continuously into the opposite side edges 29 of the generally flattened tube. As in the embodiment of FIGS. 1 and 2 expansion of the tube of FIG. 3 by internally applied pressure causes these opposite side edges 29 to be moved apart like the side edges 15 of the first embodiment into tight engagement with the similarly shaped edges 14 of the fin openings 11.

After expansion the tube of FIG. 3 does not have opposite sides quite as flat as the top and bottom sides of the tube of the first embodiment. However, because of the absence of the grooves the tube does have greater strength.

In the embodiment of FIG. 4 a pair of spaced parallel webs 30 and 31 divide the tube 32 into three parallel passages 33, 34 and 35. This tube is also of generally flatted cross section and has the opposite side edges 36 of generally wedge shape. The tube walls 37 and 39 which define these side edges and the end passages 33 and 35 are stronger so that substantially no deformation will occur under internal pressure conditions and particularly during expansion. The central chamber 34 between the webs 30 and 31, on the other hand. contain outer walls 39 and 40 in which are located hinge effect notches 4i and 42 that are similar to the grooves 23 of the first embodiment. During internal expansion the walls 39 and 40 move outwardly similar to the corresponding walls of the first embodiment to approximately a single plane for each wall. Dur ing this expansion the side edges 36 move outwardly away from each other and into tight engagement with the fin (not shown) in the same manner as the first embodiment with its fin 12.

The principal advantages of the FIG. 4 embodiment are that only the inner passage 34 is deformed at its outer walls and little or no deformation takes place in the walls 37 and 38 of the larger passages 33 and 35. The slop to the outer walls 37 and 38 permits very close contact with the assembled fins. This slope need not be a wedge shape as shown but can be of tear drop cross sectional shape or similar arrangement.

Having described our invention as related to the embodi ments shown in the accompanying drawings, it is our intention that the invention be not limited by any of the details of description, unless otherwise specified.

We claim:

I. A heat exchanger, comprising: a heat conducting fin having a noncircular opening; and a tube of similar noncircular cross section expanded to fit snugly in said opening comprising a bendable tube body having adjacent longitudinal sections connected at their adjacent edges by bendable hinge areas for bending of the tube at these areas during the expansion of said tube body.

2. The heat exchanger of claim 1 wherein eztch said hinge area comprises a thin section of said tube body.

3. The heat exchanger of claim I wherein said tube has an internal web connecting opposite sides of the tube and some of said hinge areas are located adjacent said web.

4. The heat exchanger of claim 3 wherein each said hinge area comprises a thin section of said tube body. 

1. A heat exchanger, comprising: a heat conducting fin having a noncircular opening; and a tube of similar noncircular cross section expanded to fit snugly in said opening comprising a bendable tube body having adjacent longitudinal sections connected at their adjacent edges by bendable hinge areas for bending of the tube at these areas during the expansion of said tubE body.
 2. The heat exchanger of claim 1 wherein each said hinge area comprises a thin section of said tube body.
 3. The heat exchanger of claim 1 wherein said tube has an internal web connecting opposite sides of the tube and some of said hinge areas are located adjacent said web.
 4. The heat exchanger of claim 3 wherein each said hinge area comprises a thin section of said tube body. 